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The lighting conditions under which astronauts conduct on-orbit tasks can be very extreme. Because the sun rises and sets every 45 minutes on average, operations in space must deal with very dynamic lighting, high contrast, and low light conditions for both direct and indirect viewing. Current computer based training for these operations do not have these harsh lighting conditions. The goal of this project was to investigate and measure the effects of computer aided training enhanced with static shadows, dynamic shadows and dynamic overlays to improve crew performance of Space Station tasks. Results from the project showed that under some conditions, error was reduced with the use of overlays. Consistent gender effects were noted in both training and testing performance. Use of overlays resulted in increased confidence in participants.

To work outside a space craft, humans must wear a protective suit. The required suit pressurization creates additional resistance for the wearer while performing work. How much does the suit effect work and fatigue? To answer these questions, dynamic torque was collected for the shoulder, elbow and wrist for six subjects in an Extra-vehicular Mobility Unit (EMU). In order to quantify fatigue, the subjects were to exert maximum voluntary torque for five minutes or until their maximum fell below 50% of their initial maximum for three consecutive repetitions. Using the collected torque and time data, logarithmic based functions were derived to estimate torque decay to within an absolute error of 20%. These results will be used in the development of a generalized tool for prediction of maximum available torque over time for humans using the current EMU.

A study was conducted to evaluate the performance characteristics of hand strength measurement devices in both earth gravity and zero gravity. It was noted that both hand grip and pinch strengths increased by approximately 14% in zero gravity. We believe that an exposure to zero gravity will affect the co-contracting muscle activity. More specifically, we hypothesize that the zero gravity silences or shuts down the antagonistic or anti-gravity muscles. This in turn will result in greater joint strengths when agonist muscles are activated voluntarily. This could also expose a joint to overexertion or injury situations. In summary, there is a great need to understand how zero gravity affects the musculoskeletal system from a biomechanical perspective.